1. Field of the Invention
The present invention relates to improvements in hand pump sprayers and particularly in hand pump sprayers of the trigger type.
2. Description of the Prior Art
Aerosol containers have been in widespread use for dispensing of a variety of products. These dispensers have been of particular value in dispensing viscous liquids. Commonly, a hydrocarbon propellant has been used with viscous products particularly viscous hydrocarbon based products. Under pressure in an aerosol container, hydrocarbon propellant serves as a diluent and thus reduces the viscosity and surface tension of the viscous liquid. See for example U.S. Pat. No. 3,896,975. Efforts are now under way to eliminate hydrocarbon propellants from the environment. Freon has already been banned, out of concern for the ozone layer. Other hydrocarbons such as isobutane and propane and other volatile organic compounds (VOCS) have been identified as contributing factors in air pollution in urban areas. Thus, such propellants are undesirable and need to be removed from the spray containers.
Hand pump sprayers of the trigger type are known in the art. See U.S. Pat. Nos. 3,701,478, 3,927,834 and 4,646,969 and U.S. Pat. No. 5,088,649.
Pump sprayable dispensing systems for viscous liquids have been developed in the prior art. For example, U.S. Pat. No. 5,088,649 describes a hand pump sprayer which can dispense a fine spray of viscous liquid without the need of using hydrocarbon propellants or other diluents. The fluid delivered by the hand pump sprayer of the '649 patent exits from the nozzle in two streams which collide at a point exterior to the nozzle assembly. The resulting spray pattern of such a sprayer is fan shaped. However, there are some applications where a fan shaped pattern is inconvenient.
Sprayers which have nozzles which can be rotated about their delivery passageway to allow the user to select different predetermined shaped nozzle holes are known. See U.S. Pat. No. 4,838,490. Pump sprayers which allow the movement of the nozzle outlet between two extreme positions during dispensing of the fluid are known in the art. See U.S. Pat. No. 5,152,425.